The present invention relates to an ink fountain for a printing machine, said ink fountain comprising an ink fountain roller, a bottom in the form of a blade, the edge of which is close to the ink fountain roller circumference, and two side walls in contact with the bottom of the ink fountain and sealing the sides of the ink fountain. The blade""s edge is intended to maintain a determined thickness of ink on an ink fountain roller, said blade being split into several adjacent sectors that can be shifted so as to vary the distance between the edge of the blade and the circumference of the ink fountain roller.
These blades and ink fountains are used mainly in intaglio printing machines in which the amount of ink applied to the ink fountain roller is great, so as to adequately ink the intaglio cuts in the printing plates.
Ink fountain blades and ink fountains of this type are known in the state of the art. For example, patent DD 110 632, the content of which is incorporated by reference, discloses an ink fountain, the bottom of which has a blade which is close to the circumference of the ink fountain roller. In order to vary the distance between the edge of the blade and the roller, that is to say the thickness of ink applied to the roller, the blade is deformed elastically by screws which press against the blade, on the other side thereof with respect to the ink fountain roller.
The major disadvantage of this system lies in the fact that the deformation of the blade does not allow a constant thickness of ink to be applied. This is because the profile of the deformed blade has, roughly speaking, a rounded shape because the screws press at a point location on the blade, which means that the metering of the ink is thus inaccurate.
Another system is described in patent application EP 0 600 435, the content of which is incorporated by reference. In this system, the ink fountain blade is formed of several adjacent bladelets which can be elastically deformed in order to modify the thickness of ink applied to the ink fountain roller. To obtain this deformation, use is here too made of a lever on the other side of the bladelets with respect to the ink fountain roller in order to move them closer to this roller and thus alter the distance between the edge of each bladelet and the circumference of the ink fountain roller and thus the thickness of ink applied.
This system has several drawbacks, particularly the fact that the deformation of the bladelets occurs toward the ink fountain roller. Thus, in the event of an error of manipulation, there is the risk that the blade will come into contact with the roller and damage it. The deformation of the blades also leads to fatigue in the material and this may create problems of premature wear.
The purpose of the invention is to improve the known systems.
More specifically, the object of the present invention is to provide an ink fountain in which the sealing of the side walls is markedly improved, and to do so in a simple manner and at fairly low cost. Another object of the present invention is to provide a system which can be retrofitted to existing machines, that is to say a system which can be mounted in ink fountains which are already in service without major modification thereto. Another object is to provide a segmented fountain blade which has a fine adjustment to allow a constant thickness of ink to be applied to the ink fountain roller, precisely, repeatably and without risk of damaging the roller.
The invention is characterized by the fact that the sectors forming the blade at the bottom of the ink fountain can be moved in the plane of the blade parallel to one another.
The advantages afforded by the use of a blade split into sectors according to the invention are many. Mention may, in particular, be made of the fact that the movement of the sectors is linear, which means that it is easier to control and to measure than the movement of the bladelets described in patent application EP 0 600 435. Specifically, any arbitrary point on a blade sector according to the invention has the same movement, whereas in the case of the bladelets known from the prior art, a precise measurement of the movement could be made only on the actual edge of each bladelet.
The invention will be better understood from the description of one embodiment thereof and from the figures pertaining thereto.